Interface Engineering of a Metal/ High-k/ Ge Layered Structure by Water Vapor Discharge

Abstract

The suppression of interfacial reactions in a tungsten (W)/hafnia (HfO2)/germanium (Ge) structure by water (H2O) vapor discharge was demonstrated. In the case of a HfO2/Ge dioxide (GeO2)/Ge structure, it was confirmed that the thickness of the interfacial GeO2 layer was decreased by H2O vapor discharge. Moreover, in the case of a W/hafnium (Hf)/Ge structure, it was found that such discharge can also achieve the formation of a W/HfO2/Ge structure with abrupt interfaces, without the oxidation of W or Ge. These results suggest that the selective removal of interfacial reaction layers and residual oxygen atoms in metal gate electrodes by hydrogen (H) radicals and the selective repair of oxygen-deficient high-dielectric-constant (high-k) insulators by hydroxyl (OH) and oxygen (O) radicals occur simultaneously during H2O vapor discharge. This means that thermodynamically selective etching and oxidation conditions can be realized using only H2O discharge.